We've been drooling and noshing on brains since The Walking Dead premiered back on Halloween, but we took a break from that important work to chat with TWD star Andrew Lincoln (Sheriff Rick Grimes), and here's what we learned exclusively about the show's phenomenal success and the season's upcoming and devastating last episode, "TS-19."

Crazy for Zombies: So how does Andrew feel about The Walking Dead becoming an instant hit? "I think everybody [on the show] is pinching themselves at the moment," Andrew told us in his dreamy English accent. "You always hope that people get the show the way that you do—that [The Walking Dead is about] the world zombies inhabit but it's actually about human beings, how people behave in this extraordinary environment, and I think that just makes for great drama—so that in itself is incredibly satisfying and a wonderful thing. It's one of the most talented ensemble casts I've ever had the privilege to work with. Everyone's putting in barnstorming performances. I mean they're breathtaking."

2010 Zombie Odyssey: Noah Emmerich, as the CDC's Doc Jenner, gives an especially breathtaking performance in the finale. He reluctantly welcomes his guests with food, wine...and a high-tech 3D demo of an actual human's transformation into a zombie. It's a devastating scene—especially with the reveal of Test Subject 19's identity—so have a box of Kleenex handy.

Whisper to a Scream: In their final scene together in the CDC, Doc Jenner whispers something in Rick's ear that no one else hears—including us viewers. When we asked Andrew what the good doc told him, he laughed and said, "I'm afraid I can't tell you—if I tell you I'll have to kill you and turn you into a zombie. I'm so pleased they didn't [reveal it]—because it was scripted, and extremely powerful, and I said to everyone, 'Burn this page: No one should know apart from Rick and Frank.' [Laughs.] It's brilliant that they left it [as a mystery]—it's perfect, it's so classy."

Two-Pronged Attack: One of The Walking Dead's great strengths is depicting uninfected humans as more vicious than the zombies they are fleeing. We've seen that Shane (Jon Bernthal) protects others from racist rednecks and abusive husbands, but he lacks Rick's moral center—and his conduct at the CDC will make you flinch. But of the finale's critical flashback scene between Shane and comatose Rick at the hospital, Andrew said, "You realize Shane's loyalty as a friend and as a man—and also his weaknesses. He still can't make a decision without his partner, and you realize he's flawed—everybody is under incredible duress, you see the state of the world is so extreme and terrifying that people are making split-second decisions under great duress. Is Shane barricading Rick in, or is he trying to prevent him being taken by the walkers? There are many different ways to construe what Shane has done and that's the beauty of the show is that there's no clear and definite answers, you make your own mind."

Scott Garfield/TWD Productions LLC

Icks Are for Kids: TWD isn't approved for all audiences, so we had to ask Andrew how its gory content affects its amazing child star. "Chandler Riggs [Rick's son, Carl] is a great, great actor, an incredibly talented boy," he gushed. "You do have a concern—we were doing a night shoot when the attack was happening in episode four, and there were a couple of times where I said, 'Are you OK with all of this?' but he loves it. He loves the comic book. He can't wait to go shooting guns and all getting all involved. So rest assured that it's all right—I think that he's more excited than we are. We're a bit more flinching than some of the children. But it is an ongoing concern because the subject matter is extremely grown up—but because of the intensity of the emotional scenes that we have to play out, you really get this incredible bond with everyone."

Don't miss your chance to bond with The Walking Dead! The AMC marathon begins at 4:30 p.m. Sunday, concluding with the finale at 10 p.m.